Bateriocin

Bacteriocins:

1. Introduction :

★ Bacteriocins are antimicrobial peptides produced by bacteria that inhibit the growth of similar or closely related bacterial strains.

★ They are ribosomally synthesized and can be used as natural preservatives and alternatives to antibiotics.

2. Classification of Bacteriocins :

Based on structure and function:

★ Class I (Lantibiotics): Contain unusual amino acids (e.g., nisin).

★ Class II: Small, heat-stable peptides (e.g., pediocin).

★ Class III: Large, heat-labile proteins.

★ Class IV: Complex proteins with lipid or carbohydrate moieties.

3. Production of Bacteriocins

3.1. Producing Organisms

> Common producers: Lactic acid bacteria (LAB) such as Lactobacillus, Pediococcus, Lactococcus, Enterococcus.


3.2. Genes and Regulation

> Genes responsible for:

> Bacteriocin production

>Immunity proteins (protect the producer)

> Transport and secretion

>Often found on plasmids or chromosomal DNA.


3.3. Production Conditions

> pH: Optimal around 5.0–6.5

> Temperature: 30–37°C for LAB

> Nutrient-rich media enhances yield


3.4. Purification Techniques

>Ammonium sulfate precipitation

>Gel filtration chromatography

>Reverse-phase HPLC

4. Mechanism of Action

> Disrupt target cell membranes by pore formation

> Depolarization and leakage of essential ions

>Inhibition of cell wall synthesis (some lantibiotics)

5. Health Benefits

5.1. Antimicrobial Activity

>Active against Gram-positive bacteria, including pathogens like Listeria monocytogenes, Clostridium, and Staphylococcus.

>Nisin is approved as a food preservative (E234).


5.2. Gut Microbiota Modulation

>Promotes beneficial microbes

>Helps suppress harmful bacteria without disturbing commensals


5.3. Alternatives to Antibiotics

>Useful in treating antibiotic-resistant infections

>Lower risk of resistance development


5.4. Anti-Cancer Potential

>Some bacteriocins show cytotoxic effects on cancer cell lines (under research)


5.5. Immune Modulation

>May enhance host immunity indirectly by modulating microbiotation.

6. Applications

★ Food industry: Natural preservatives to enhance shelf-life (e.g., dairy, meat)

★ Medicine: Potential therapeutic agents against resistant infections

★ Veterinary: Alternatives to growth-promoting antibiotics in animals

★ Agriculture: Biocontrol agents against plant pathogens

7. Limitations and Challenges

★ Narrow spectrum of activity

★;Limited effectiveness against Gram-negative bacteria

★ Production cost and scale-up

★ Regulatory approval for medical uses.

8. Future Prospects

★ Genetic engineering to enhance production and broaden spectrum

★ Synergistic use with other antimicrobials

★ Clinical trials for medical applications

★ Use in synbiotics and functional foods.



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